1. Field of the Invention
The present invention relates to urinary incontinence and, more particularly, to systems and methods for treating stress urinary incontinence.
2. Description of the Related Art
Urinary incontinence (UI) is any involuntary leakage of urine. It is a common and distressing problem that may have a profound impact on quality of life. UI often results from an underlying treatable medical condition.
Continence and urination involve a balance between urethral closure and detrusor muscle activity. Urethral pressure normally exceeds bladder pressure, resulting in urine remaining in the bladder. The proximal urethra and the bladder are both within the pelvis. Intra-abdominal pressure increases, e.g., from coughing and sneezing, are typically transmitted to both the urethra and the bladder equally, leaving the pressure differential unchanged, resulting in continence. Normal urination is the result of changes in both of these pressure factors, i.e., urethral pressure decreasing and bladder pressure increasing.
UI affects women of all ages, however, UI is highly prevalent in women across their adult life span and its severity increases linearly with age. Up to 35% of the total population over the age of 60 years is estimated to have UI, with women twice as likely as men to experience UI. One in three women over the age of 60 years are estimated to have UI.
A leading form of UI is known as stress urinary incontinence (SUI). SUI is essentially due to pelvic floor muscle weakness. It results in a loss of small amounts of urine with coughing, laughing, sneezing, exercising or other movements that increase intra-abdominal pressure and thus increase pressure on the bladder. Physical changes resulting from pregnancy, childbirth and menopause often cause SUI.
The urethra is supported by fascia of the pelvic floor. If the fascial support is weakened, as it can be from pregnancy, childbirth or normal physiological changes in the body over the course life, the urethra can move downward at times of increased abdominal pressure, resulting in SUI.
A surgical procedure for treating SUI employs what is commonly referred to as a sling. A sling may consist of any desired material in any desired shape but often consists of a synthetic mesh material or a mesh of biomaterial, e.g., bovine, porcine or the patients' own tissue, in the shape of a ribbon that is placed under the urethra. In practice, a sling surgically implanted beneath a patient's urethra replaces the deficient pelvic floor muscles and provides structural support under the urethra that is sufficient to limit or eliminate SUI.
A common surgical procedure for implanting a sling is referred to as the transobturator procedure. With this procedure, a pair of incisions are made near the groin at the level of the obturator fossa of the pelvic bone and one in the vagina. Sling carriers are passed through from the groin incisions to the vaginal incision. Extension arms connected to the sling are fixedly attached to the sling carriers and the sling carriers are moved to withdraw the extension arms from the pair of incisions made near the groin and to position the sling under the urethra. Thereafter, the extension arms are cut to free the sling carriers, sling tension is adjusted and the incision is closed.
The transobturator procedure involves passing the sling carriers from the two incisions made near the groin at the obturator of the pelvic bone to the vaginal incision. By necessity then, the sling carriers pass through the patient, increasing patient trauma that may include nerve damage. To limit such patient trauma, a less invasive surgical procedure has emerged in which a sling is implanted but only a single vaginal incision is required. However, existing slings, whether implanted using only a vaginal incision or the multiple-incision transobturator procedure, have further limitations, including the inability to reposition the sling.
For example, some current slings include an anchoring mechanism, such as a barbed fastener located at each end of the sling for implanting into the patient's tissue. The anchoring mechanism provides holding strength for the sling until post-surgical tissue growth enables the patient's tissue to provide supplemental long-term holding strength for the sling. It is not uncommon for a surgeon to improperly implant the sling, i.e., when device placement is not optimum for treatment of SUI. At such times, the surgeon must completely remove the sling from the patient and attempt to properly implant the removed sling.
To remove an improperly placed sling, a surgeon typically uses his or her hand, a surgical tool, e.g. a hemostat, or some combination thereof to grasp a portion of the sling and remove it from the patient. The process for removing the sling, once implanted in the patient, is difficult because it is not easy for the surgeon to see and grasp the implanted sling. Moreover, assuming the surgeon can even see or locate an improperly implanted sling, the surgeon must grasp whatever portion of the sling that he or she can to remove the device. Typically, the surgeon grasps an improperly implanted sling at a single position somewhere on the sling and employs considerable force to remove the device. The process of removing an improperly implanted sling using such considerable retraction force applied to a single position on the sling often damages the device. Specifically, the sling is often stretched or torn such that it cannot be reused. In such instances, the surgeon must use another sling to complete the procedure, resulting in increased cost for the procedure.
Even for slings that do not include an anchoring mechanism, such as a barbed fastener located at each end of the sling, device removal is an issue for an improperly implanted sling. In such instances, following device implantation with the transobturator procedure, the sling carriers which are fixed to the sling extension arms cannot be backed out to remove the sling from beneath the urethra. Accordingly, it is not possible to remove the sling for repositioning, if desired.
Existing slings also have limited holding strength. As noted above, post-surgical tissue growth enables the patient's tissue to provide supplemental long-term holding strength for the sling. However, until such time that post-surgical tissue growth enables the patient's tissue to provide supplemental long-term holding strength for the sling, means for providing preliminary holding strength are employed. Such preliminary holding strength systems include those which employ an anchoring mechanism, such as a barbed fastener located at each end of the sling, for implanting into the patient's tissue. Other slings do not employ an anchoring mechanism and simply rely on a friction fit between the sling and the patient's tissue to hold the sling in place. Regardless of the type of preliminary holding strength system that is employed, current slings continue to move following surgery, and therefore, would benefit from improved holding strength.
A need exists for systems and methods for treatment of SUI, which overcome these and other problems associated with the prior art.